Three stage emulsion and suspension in process for production of impact resistant thermoplastic resins

ABSTRACT

Thermoplastic resins capable of forming molded articles having few flow marks, and a high falling ball impact strength can be produced by polymerizing (I) 1 to 30 percent by weight of tricyclodecenyl acrylate or methacrylate, (II) 50 to 99 percent by weight of at least one alkyl acrylate in which the alkyl group has 1 to 13 carbon atoms and (III) 0 to 20 percent by weight of at least one vinyl compound copolymerizable with said alkyl acrylate (II), in an aqueous emulsion to form a copolymer (A), radical-polymerizing, in the presence of 50 to 90 percent by weight (on solid basis) of the thus obtained aqueous copolymer (A) emulsion, 50 to 10 percent by weight of a monomer mixture (B) comprising 0 to 60 percent by weight of methyl methacrylate, 25 to 80 percent by weight of an aromatic vinyl monomer, 6 to 30 percent by weight of acrylonitrile, and 1 to 10 percent by weight of at least one monomer selected from the group consisting of tricyclodecenyl acrylate, tricyclodecenyl methacrylate, and nonconjugated divinyl compounds, to form a pre-graft-copolymer (C), and subsequently subjecting to graft-copolymerization 10 to 40 percent by weight (on solid basis) of the thus obtained aqueous pre-graft-copolymer (C) emulsion and 90 to 60 percent by weight of a monomer mixture (D) comprising 30 to 60 percent by weight of methyl methacrylate, 60 to 30 percent by we

United States Patent n91 Kakefuda et al.

11] 3,711,575 1 Jani 16,1973

[75] Inventors: Koiti Kakel'uda; Tatsuo Ito, both of Ichihara; YasuyukiOkano, Hitachi, all of Japan [73] Assignee: Hitachi Chemical Company,Ltd.,

- Tokyo,.lapan [22] Filed: Jan. 28, 1971 [21] Appl. No.: 110,637

[30] 7 Foreign Application Priority Data Feb. 6 l970 I Japan ..45/l0()35[52] U.S. CL. ..260/881, 260/29.6 RB, 260/883 [51] Int. Cl. ..C08f 15/40v [58] Field of Search ..260/88l, 29.6 RB

[56] References Cited UNITED STATES PATENTS 6/l969 Ryan et al. ..260/8766/1969 Griffin ..260/885n Primary ExaminerMurray Tillman AssistantExaminer-John Seibert Att0rneyCraig, Antonelli & Hill 14 Claims, NoDrawings THREE STAGE EMULSION AND SUSPENSION IN PROCESS FOR PRODUCTIONOF IMPACT RESISTANT THERMOPLASTIC RESINS The present invention relatesto a process for producing thermoplastic resins resistant to weatheringand impact.

As an impact resistant molding material, therehas been known athermoplastic resin called ABS resin, made from acrylonitrile, styreneand butadiene as the main components. The ABS resin, however, is notcompletely satisfactory in weather-resistance, the improvement of whichhas strongly been desired. Since the unsatisfactory weather-resistanceof ABS resin originates mainly from the susceptibility of the butadienecomponent to the degrading action of oxygen or ultraviolet rays, therehave been made various attempts to substitute for the butadienecomponent other rubber-like materials that are more weather-resistant.The present inventors disclosed in Japanese Pat. publication No. 8987/70a process forproducing a thermoplastic resin having excellent resistanceto both weathering and impact by graft-copolymerizing styrene,acrylonitrile and the like, on a copolymer of tricyclodecenyl acrylateor tricyclodecenyl methacrylate with an alkyl acrylate.

The present inventors continued research on said graft copolymer andfound that when the thermoplastic resin obtained by graft-copolymerizingstyrene and acrylonitrile on a copolymer of tricyclodecenyl acrylate ortricyclodecenyl methacrylate with an alkyl acrylate is injection-molded,most of the resulting molded articles have, on their surfaces, wave-likemarks that reduce their commercial value (such marks being hereinafterreferred to as flow marks).

The object of the present invention is to provide a process forproducing a thermoplastic resin capable of forming molded articleshaving very few flow marks and an enhanced impact resistance.

As a result of further efforts to reduce the flow marks, the presentinventors found that a thermoplastic resin capable of forming moldedarticles having markedly reduced flow marks can be produced bypolymerizing tricyclodecenyl acrylate or tricyclodecenyl methacrylatewith an alkyl acrylate such as butyl acrylate in an aqueous emulsion,and then, graftcopolymerizing, in the presence of the resultingcopolymer emulsion, a monomer mixture comprising 30 to 60 percent byweight of methyl methacrylate, 60 to 30 percent by weight of styrene and8 to 21 percent by weight of acrylonitrile. However, when methylmethacrylate was thus introduced into the polymer, the falling ballimpact strength of the molded articles is decreased with an increase ofthe amount of methyl methacrylate used. Therefore, a further improvementwas required from a practical point of view. As a result of additionalstudies the present inventors have succeeded in said improvement.

According to the present invention, there is provided a process forproducing thermoplastic resins capable of forming molded articles havingvery few flow marks and high falling ball impact resistance,whichcomprises polymerizing (l) l to 30 percent by weight oftricyclodecenyl acrylate, i.e., tricyclo [5.2.1 .0 -]dec-3- en-8(or-9)-gl acrylate, or tricyclodecenyl methacrylate, i.e., tricyclo[5.2.1.0 ]dec-3-en-8(or 9) methacrylate, (II)5O to 99 percent by weightof at least one alkyl acrylate in-which the alkyl group has one to l3carbon atoms, and (Ill) 0 to 20 percent by weight of at least one vinylcompound copolymerizable with said alkyl acrylate (II), in an aqueousemulsion to form a copolymer (A), then radical-polymerizing in thepresence of 50 to 90 percent by weight (on solid basis) of the thusobtained aqueous copolymer (A) emulsion, 50 to 10' percent by weight ofa monomer mixture (B) comprising 0 to 60 percent by weight of methylmethacrylate, 25 to percent by weight of an aromatic vinyl monomer, 6 to30 percent by weight of acrylonitrile and l to 10 percent by weight ofat least one monomer selected from the group consisting oftricyclodecenyl acrylate, tricyclodecenyl methacrylate andnon-conjugated divinyl compounds, to form a pregraft-copolymer (C), andsubsequently subjecting to graft-copolymerization 10 to 40 percent byweight (on solid basis) of the thus formed aqueous pre-graftcopolymer(C) emulsion and to 60 percent by weight of a monomer mixture (D)comprising 30 to 60 percent by weight of methyl methacrylate, 60 to 30percent by weight of an aromatic vinyl monomer and 8 to 21 percent byweight of acrylonitrile, in the presence of a radical-polymerizationinitiator and a partially saponified polyvinyl alcohol in an amountsufficient to convert the emulsion into a suspension in the course ofpolymerization.

The tricyclodecenyl acrylate or tricyclodecenyl methacrylate (I) for useinthis invention is a compound obtained by reacting dicyclopentadienewith acrylic acid or methacrylic acid in the presence of a catalyst suchas BF the structural formula of said compound being assumed to be asfollows:

wherein R is H or CH,,.

The vinyl compound (Ill) copolymerizable with component (II) used inthis invention includes, for example, styrene, oz-methylstyrene,acrylonitrile, methacrylonitrile, alkyl vinyl ethers, such as n-butylvinyl ether, acrylic acid, methacrylic acid, alkyl acry- Iates, such asmethyl acrylate and ethyl acrylate, alkyl methacrylates, such as methylmethacrylate and ethyl acrylate, acrylamide and methacrylamide.

The aromatic vinyl monomers used in this invention include styrene,a-methylstyrene, a-ethylstyrene, and derivatives of these compoundshaving substituents on the nucleus such as, for example, vinyltoluene,chlorostyrene, and the like.

In this invention, the non-conjugated divinyl compound is selected fromdivinyl compounds such as divinylbenzene; diol esters of unsaturatedacids such as ethylene glycol diacrylate and ethylene glycoldimethacrylate; esters of unsaturated alcohol with unsaturated acidssuch as allyl acrylate and allyl methacrylate', and esters ofunsaturated alcohol with polybasic acids such as diallyl phthalate andtriallyl cyanurate.

The polymerization initiators useful in the preparation of copolymer (A)include initiators for ordinary emulsion polymerizations such as, forexample, persulfates, a redox initiator composed of cumene hydroperoxideand sodium formaldehyde sulfoxylate and the like. As the emulsifier,anionic emulsifiers such as sodium oleate are used, though nonionicemulsifiers may be used in combination with the anionic emulsifiers. Inpreparing the copolymer (A), it is more preferable in polymerizationtemperature control, particle size control and reduction of amount ofagglomerate than charging the whole amount of the emulsifier or themonomer at once, to charge at the start of polymerization a portion ofthe emulsifier or the monomer and continue the polymerization whilecontinuously or portionwise adding the remaining emulsifier or monomeraccording to the progress of polymerization.

The temperature to be maintained during the polymerization reaction mayvary depending upon the kind of polymerization initiator used, and thereare suitable temperature ranges for the respective initiators, thoughpreferably 30 60C.

According to circumstances, the use of a pH regulating agent andanti-foaming agent should be taken into account.

In preparing the pre-graft-copolymer (C), a chain transfer agent such astert-dodecyl mercaptan should not be used. Also, consideration shouldpreferably be given so that the polymerization may be initiated afterthe copolymer (A) has sufficiently been swollen with the monomer mixtureused. It is undesirable that significant amounts of the tricyclodecenylacrylate, the tricyclodecenyl methacrylate and the non-conjugateddivinyl compound remains unpolymerized after termination of thepolymerization. Therefore, consideration should be given to the properselection of polymerization initiator, polymerization temperature, andpolymerization time so as to increase the conversion as much aspossible.

The polymerization temperature is desirably higher than that in theproduction of the copolymer (A) and preferably within the range of 60 to90C.

In the final polymerization step, a chain transfer agent such astert-dodecyl mercaptan is preferably used in an amount of, ordinarily, 1percent or less based on the monomer. As for the radical-polymerizationinitiator, it is preferable to freshly add a persulfate or a redox-typeinitiator such as a combination of cumen hydroperoxide and sodiumformaldehyde sulfoxylate. It is also possible to use the above-saidinitiators in combination with an oil-soluble polymerization initiatorsuch as lauroyl peroxide, benzoyl peroxide, azobisisobutyronitrile orthe like.

The polymerization temperature is preferably higher than 60C, though maysuitably be selected depending upon the kind of polymerization initiatorused.

The partially saponified polyvinyl alcohol to be used for the purpose ofsmoothly converting the emulsion phase into a suspension phase in thecourse of polymerization has preferably a polymerization degree of 1,000to 2,000 and a saponification degree of 80 to percent. However, there isno strict limit to these ranges, and they should suitably be chosenaccording to the kind and amount of the emulsifier used. Also, beforestarting polymerization, the reactant mixture can be'treated by means ofT.K. Homomixer (made by Tokushu Kika Kogyo Co., Ltd.)

The polymerization in this step proceeds in the form of an emulsionpolymerization at the early stage. As the polymerization proceedsfurther on, the aggregation of particles takes place, and when thepolymerization conversion exceeds about 60 percent, the viscosity of thepolymerization system increases more and more and smooth agitationbecomes increasingly difficult. At such a stage, deionized water aloneor that containing dissolved therein up to 0.5 percent by weight ofpartially saponified polyvinyl alcohol is added to the system to convertthe polymerization system to a suspension state without trouble such asformation of a sticky mass, whereby the subsequent polymerization can becarried out with smooth agitation.

Since the resulting resin is in the form of easily filterable smallparticles, no salting-out procedure as used in an ordinary emulsionpolymerization is necessary in this case.

The present invention is further explained in detail with reference tothe following examples, which are presented merely by way ofillustration and not by way of limitation. In the examples, all partsand percentages are by weight, unless otherwise specified.

EXAMPLE 1 Recipe: Component 1 Ferrous sulfate heptahydrate 0.0006 partDisodium ethylenediamine tctraacetate dihydratc 0.0012 part Sodiumformaldehyde sulfoxylate 1.5 part Sodium oleate 60 part Deionized water720.0 part Component ll Butyl acrylate 294.0 pans Tricyclodcccnylmethacrylate 6.0 parts Cumene hydroperoxide 0.5 parts Component lllStyrene 45.0 parts Acrylonitrile l5.0 parts Tricyclodeccnyl methacrylate1.2 parts Component IV Partially saponified polyvinyl alcohol (KH-l 7,Nippon Gosei Kagaku Co., Ltd.) 2.2 parts Sodium formaldehyde sulfoxylate0.5 parts Dcionized water 520.0 parts Component V Methyl methacrylatcl42.0 pans Styrene I430 parts Acrylonitrile 7L0 parts Lauroyl peroxide0.5 parts terl-Dodccyl mercaptan L45 parts Cumcne hydrOpCl'OXldL' 0.7!parts Component Vl Partially saponilicd polyvinyl alcohol (KH-l 7) L0part Deionized water percent, 499.0 parts Polymerization procedureComponent 1 was charged into a reactor, and after the air in the reactorwas replaced by nitrogen, 10 percent i.e. 30.0 parts, of component llwas added thereto with stirring, after which the temperature of themixture was elevated to 50C. After most of the monomer initially chargedhad been polymerized, the remainder of component ll was continuouslycharged over a period of 5 hours while the polymerization temperaturewas controlled at 50C to polymerize the monomer. After completion of theaddition of component 11, the mixture was kept at 50C for 2 hours tosubstantially complete the polymerization. The resulting rubber-likeresin is hereinafter referred to as copolymer (A). After the reactor wascooled to a temperature below 30C, component 111 was added thereto, andthe resulting mixture was stirred for one hour while the temperature wasadjusted so as not to exceed 30C by cooling. After the lapse of 1 hour,the mixture was heated to 70C, and as soon as the temperature reached70C, 0.2 part of cumene hydroperoxide was added dropwise, and thetemperature was kept at 70C for 3 hours to effect polymerization, afterwhich the mixture was cooled to obtain a latex of a pre-graft-copolymer(C).

lnto another reactor were charged components 1V and V, and the air inthe reactor was replaced by nitrogen with stirring. The latex ofpre-graft-copolymer (C) in'an amount corresponding to 120.0 parts ofcopolymer (A) contained therein was slowly added to the reactor, and themixture was stirred at room temperature for l hour, after which thetemperature was raised to 70C. After 6 hours of stirring at 70C, theviscosity of the polymerization mixture increased so that smoothstirring became difficult. At this stage, component VI was added to themixture to decrease the viscosity, and consequently, restore the smoothstirring. The temperature which had been lowered below 60C was elevatedto 80C, and polymerization was allowed to proceed at this temperaturefor 5 hours. The resulting slurry was filtered, dehydrated, washed withwater and then dried. The dried powder was extruded from an extruder andpelletized. The resin thus obtained was injection-molded to obtain testpieces havingasize of2 X40 X 120 mm.

The surface of the test pieces was inspected for flow marks, and thefalling ball impact strength of the test piece was determined by meansof a Du Pont falling ball impact tester. The impact strength at abreakage of 50 percent was taken as the falling ball impact strength.

REFERENTIAL EXAMPLE 1 1n the same manner as in Example 1, test pieceswere obtained except that component 11] was composed of 45.0 parts ofstyrene and 15.0 parts of acrylonitrile.

The results obtained in Example 1 and Referential Example 1 were asshown in Table I.

The same procedure as in Example 1 was repeated to obtain test pieces,except that the composition of component 111 was changed as follows:

Methyl methaerylate 24.0 parts Styrene 24.0 parts Aerylonitrile 12.0parts Tricyclodecenyl methacrylate 1.2 parts REFERENTIAL EXAMPLE 2 Thesame procedure as in Example 1 was repeated to obtain test pieces,except that the composition of component 111 was changed as follows:

Methyl methacrylate 24.0 parts Styrene 24.0 parts Acrylonitrile 12.0parts REFERENTIAL EXAMPLE 3 The same procedure as in Example 1 wasrepeated, except that the pre-graft-polymerization by use of component111 was omitted and the composition of component V was changed asfollows:

Methyl methacrylate 152.0 parts Styrene 152.0 parts Acrylonitrile 76.0parts Lauroyl peroxide 0.5 parts Cumene hydroperoxide 0.76 partstert-Dodecyl mercaptan 1.45 parts The results obtained in Example 2 andReferential Examples 2 and 3 were as shown in Table 2.

Example 1 was repeated, except that the composition of component V wasas follows:

Methyl methacrylate 142.0 parts Styrene 164.0 parts Acrylonitrile 50.0parts Lauroyl peroxide 0.5 parts Cumene hydroperoxide 0.71 partstert-Dodecyl mercaptan 1.45 part REFERENTIAL EXAM PLE 4 The procedure ofExample 3 was repeated, except that component V was changed to thefollowing composition:

Styrene 2670 parts Acrylonitrilc 89.0 parts Lauroyl peroxide 0.5 partsCumene hydroperoxide 0.71 parts tert-Dodecyl mercaptan 1.45 partsREFERENTIAL EXAMPLE 5 The same procedure as in Example 3 was repeatedexcept that the component V was changed as follows:

Styrene 285.0 parts Acrylonitrile 95.0 parts Lauroyl peroxide 0.5 partsCumene hydroperoxide 0.76 parts tert-Dodecyl mcrcaptan 1.45 parts Theresults obtained in Example 3 and Referential Examples 4 and 5 were asshown in Table 3.

TABLE 3 Amount of Item Pre-graftmethyl Falling ball polymerizationmethacrylate Flow impact tion using in component mark strength Testcomponent lll (kg-cm) piece lll Example 3 Yes 40 No. 50 ReferentialExample 4 Yes Yes 50 Referential Example No. 0 Yes 30 EXAMPLE 4 For thecomponent Ill in Example 1 were substituted the following:

Styrene 45.0 parts Acrylonitrile 15.0 Tricyclodecenyl methacrylute2.4

EXAMPLE 5 For the component ll in Example 1 were substituted thefollowing:

Butyl acrylate 285.0 parts Tricyclodecenyl methacrylate 15.0 Cumenehydroperoxide 0.5

REFERENTIAL EXAMPLE 6 For the component III in Example 5 weresubstituted the following:

Styrene 45.0 parts Acrylonitrile l5.0 parts The results obtained inExamples 4 and 5 and Referential Example 6 were as shown in Table 4.

EXAMPLE 7 The following were substituted for the component III inExample 6:

Styrene 45.0 parts Acrylonitrile 15.0 parts Tricyclodeeenyl acrylate 1.2parts TABLE 5 Falling ball impact strength g Flow mark Component llComponent lil Test piece Tricyclodecenyl methacrylate I 369271Tricyclodece nyl acrylate L96?! Tricyclodeeenyl Example 6 acrylate 2.071

Example Tricyclodccenyl No 50 7 acrylate 2.0

What is claimed is:

l. A process for producing an impact resistant, thermoplastic resinhaving few flow marks, which comprises (l) polymerizing (l) l to 30percent by weight of tricyclodecenyl acrylate or tricyclodecenylmethacrylate, (ll) 50 to 99 percent by weight of at least one alkylacrylate in which the alkyl group has one to 13 carbon atoms and (ill) 0to 20 percent by weight of at least one vinyl compound copolymerizablewith said alkyl acrylate (ll), in an aqueous emulsion to form acopolymer (A), then (2) radical-polymerizing, in the presence of 50 to90 percent by weight, on solid basis, of the resulting aqueous copolymer(A) emulsion, 50 to 10 percent by weight of a monomer mixture (B)comprising 0 to 60% by weight of methyl methacrylate, 25 to percent byweight of an aromatic vinyl monomer, 6 to 30 percent by weight ofacrylonitrile and l to 10 percent by weight of at least one monomerselected from the group consisting of tricyclodecenyl acrylate,tricyclodecenyl methacrylate and non-conjugated divinyl compounds, toform a pregraft-copolymer (C), (3) subsequently subjecting tograft-copolymerization 10 to 40 percent by weight, on solid basis, ofthe thus obtained aqueous pregraft-copolymer (C) emulsion and to 60percent by weight of a monomer mixture (D) comprising 30 to 60 percentby weight of methyl methacrylate, 60 to 30 percent by weight of anaromatic vinyl monomer and 8 to 21% by weight of acrylonitrile, in thepresence of a radical-copolymerization initiator and (4) adding duringsuch graftcopolymerization a partially saponified polyvinyl alcohol inan amount sufficient to convert the emulsion to a suspension in thecourse of the polymerization.

2. A process according to claim 1, wherein the component (III) isselected from the group consisting of styrene, a-methylstyrene,acrylonitrile, methacrylonitrile, alkyl vinyl ethers, acrylic acid,methacrylic acid, alkyl acrylates, alkyl methacrylates, acrylamide andmethacrylamide.

3. A process according to claim 1, wherein the aromatic vinyl monomer isselected from the group consisting of styrene, a-methylstyrene,a-ethylstyrene, vinyl toluene and chlorostyrene.

4. A process according to claim 1, wherein the nonconjugated divinylcompound is selected from the group consisting of divinylbenzene,ethylene glycol diacrylate, ethylene glycol dimethacrylate, allylacrylate, allyl methacrylate, diallyl phthalate and triallyl cyanurate.

5. A process according to claim 1, wherein the copolymer (A) is formedin the presence of a polymerization initiator of the redox type.

6. A process according to claim 1, wherein the graftcopolymerization ofthe monomer mixture (D) on the pre-graft-copolymer (C) is effected inthe presence of a chain transfer agent.

7. A process according to claim 6, wherein the amount of the chaintransfer agent is 1 percent by weight or less based on the weight ofcomponent (D).

8. A process according to claim 6, wherein the chain transfer agent istert-dodecyl mercaptan.

9. A process according to claim 1, wherein the partially saponifiedpolyvinyl alcohol has a polymerization degree of 1,000 to 2,000 and asaponification degree of 80 to 90 percent.

10. An impact resistant, thermoplastic resin obtained according to theprocess of claim 1.

11. A process according to claim 1, wherein said partially saponifiedpolyvinyl alcohol is added when the viscosity of the emulsion during thegraftcopolymerization has increased such that smooth agitation becomesdifficult.

12. A process according to claim 11, wherein the polyvinyl alcohol isadded when the polymerization conversion exceeds about 60%.

13. A process according to claim 1. wherein. the tricyclo-decenylacrylate or tricyclodecenyl methacrylate have the formula:

o R -o-i i-t bonz

1. A process for producing an impact resistant, thermoplastic resinhaving few flow marks, which comprises (1) polymerizing (I) 1 to 30percent by weight of tricyclodecenyl acrylate or tricyclodecenylmethacrylate, (II) 50 to 99 percent by weight of at least one alkylacrylate in which the alkyl group has one to 13 carbon atoms and (III) 0to 20 percent by weight of at least one vinyl compound copolymerizablewith said alkyl acrylate (II), in an aqueous emulsion to form acopolymer (A), then (2) radicalpolymerizing, in the presence of 50 to 90percent by weight, on solid basis, of the resulting aqueous copolymer(A) emulsion, 50 to 10 percent by weight of a monomer mixture (B)comprising 0 to 60% by weight of methyl methacrylate, 25 to 80 percentby weight of an aromatic vinyl monomer, 6 to 30 percent by weight ofacrylonitrile and 1 to 10 percent by weight of at least one monomerselected from the group consisting of tricyclodecenyl acrylate,tricyclodecenyl methacrylate and non-conjugated divinyl compounds, toform a pregraft-copolymer (C), (3) subsequently subjecting tograft-copolymerization 10 to 40 percent by weight, on solid basis, ofthe thus obtained aqueous pregraft-copolymer (C) emulsion and 90 to 60percent by weight of a monomer mixture (D) comprising 30 to 60 percentby weight of methyl methacrylate, 60 to 30 percent by weight of anaromatic vinyl monomer and 8 to 21% by weight of acrylonitrile, in thepresence of a radicalcopolymerization initiator and (4) adding duringsuch graftcopolymerization a partially saponified polyvinyl alcohol inan amount sufficient to convert the emulsion to a suspension in thecourse of the polymerization.
 2. A process according to claim 1, whereinthe component (III) is selected from the group consisting of styrene,Alpha -methylstyrene, acrylonitrile, methacrylonitrile, alkyl vinylethers, acrylic acid, methacrylic acid, alkyl acrylates, alkylmethacrylates, acrylamide and methacrylamide.
 3. A process according toclaim 1, wherein the aromatic vinyl monomer is selected from the groupconsisting of styrene, Alpha -methylstyrene, Alpha -ethylstyrene, vinyltoluene and chlorostyrene.
 4. A process according to claim 1, whereinthe non-conjugated divinyl compound is selected from the groupconsisting of divinylbenzene, ethylene glycol diacrylate, ethyleneglycol dimethacrylate, allyl acrylate, allyl methacrylate, diallylphthalate and triallyl cyanurate.
 5. A process according to claim 1,wherein the copolymer (A) is formed in the presence of a polymerizationinitiator of the redox type.
 6. A process according to claim 1, whereinthe graft-copolymerization of the monomer mixture (D) on thepre-graft-copolymer (C) is effected in the presence of a chain transferagent.
 7. A process according to claim 6, wherein the amount of thechain transfer agent is 1 percent by weight or less based on the weightof component (D).
 8. A process according to claim 6, wherein the chaintransfer agent is tert-dodecyl mercaptan.
 9. A process according toclaim 1, wherein the partially saponified polyvinyl alcohol has apolymerization degree of 1,000 to 2,000 and a saponification degree of80 to 90 percent.
 10. An impact resistant, thermoplastic resin obtainedaccording to the process of claim
 1. 11. A process according to claim 1,wherein said partially saponified polyvinyl alcohol is added when theviscosity of the emulsion during the graft-copolymerization hasincreased such that smooth agitation becomes difficult.
 12. A processaccording to claim 11, wherein the polyvinyl alcohol is added when thepolymerization conversion exceeds about 60%.
 13. A process according toclaim 1, wherein, the tricyclo-Decenyl acrylate or tricyclodecenylmethacrylate have the formula: or wherein R is H or CH3.
 14. A processaccording to claim 1, wherein, the tricyclodecenyl acrylate is tricyclo(5.2.1.02,6)dec-3-en-8(or -9)-yl acrylate and the tricyclodecenylmethacrylate is tricyclo(5.2.1.02,6)dec-3-en-8(or -9)-yl methacrylate.